A high-voltage traction battery may be used for hybrid and electric vehicle applications. The high-voltage traction battery is typically connected to a battery controller that has specialized circuitry to measure each cell of a high-voltage string. During manufacturing, the connector of the controller must be physically connected to the battery cells via harnesses and connectors. Pins within the connectors mate to complete the cell measurement circuits. These connections are made when the circuits are fully powered which is referred to as a hot plug connection. Likewise, during service, the connector of the battery controller may be disconnected and reconnected when the circuits are fully powered.
The order in which the connector pins actually mate is random due to several factors including variations in pin length, seating depth, and angle of connector insertion/extraction. There are patterns of connection/disconnection order that may cause momentary unpredictable voltage conditions within the battery controller circuitry including overvoltage and reverse voltage biasing of components. The stressed components may become immediately inoperative or may be compromised such that they do not meet design durability goals.
A battery controller's susceptibility to this failure mode may not be evident even after several connections due to the unpredictable nature of the connections. A relatively small number of connections may not have included the most stressful pin mating order. Mildly stressful connections may result in cumulative component stress that allows the battery controller to function until a sufficient number of mildly stressful connections/disconnections are performed.